Typically fingerprints have been imaged using contact based fingerprint readers that require a subject's finger to be in contact with a screen and then physically rolled across the screen to provide a full rolled-image fingerprint. Systems have been developed using a single flat image, but these do not provide the entire fingerprint data due to the imaging technique that creates contrast between fingerprint ridges and valleys, which are in contact with a glass window and a shallow depth-of-field of most imaging system which prevents all areas of the finger, for example the tops and sides, from being in clear focus in the same image. Multiple image systems have been used to allow data capture using multiple focal points, however the ability to quickly capture the multiple images needed is limited by the means to shift the focus position quickly. Also, the speed of the system must be such that the small movement of a person holding their finger in place for imaging does not degrade the quality or position of the multiple images required.
Therefore a system is needed to collect fast images of a fingerprint without physical contact with the image reader, at a speed consistent with finger stability, and which can subsequently be compared to a rolled-image fingerprint.